From nobody Thu Dec 18 20:31:59 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id F1533EEB57B for ; Sat, 9 Sep 2023 03:24:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240345AbjIIDYG (ORCPT ); Fri, 8 Sep 2023 23:24:06 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59148 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233986AbjIIDXh (ORCPT ); Fri, 8 Sep 2023 23:23:37 -0400 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 466251FE0 for ; Fri, 8 Sep 2023 20:23:33 -0700 (PDT) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 808A7C433B8; Sat, 9 Sep 2023 03:23:31 +0000 (UTC) Received: from rostedt by gandalf with local (Exim 4.96) (envelope-from ) id 1qeoZa-000Yhj-08; Fri, 08 Sep 2023 23:23:50 -0400 Message-ID: <20230909032349.854283780@goodmis.org> User-Agent: quilt/0.66 Date: Fri, 08 Sep 2023 23:16:24 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Masami Hiramatsu , Mark Rutland , Andrew Morton , Zheng Yejian Subject: [for-linus][PATCH 09/15] ring-buffer: Avoid softlockup in ring_buffer_resize() References: <20230909031615.047488015@goodmis.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Zheng Yejian When user resize all trace ring buffer through file 'buffer_size_kb', then in ring_buffer_resize(), kernel allocates buffer pages for each cpu in a loop. If the kernel preemption model is PREEMPT_NONE and there are many cpus and there are many buffer pages to be allocated, it may not give up cpu for a long time and finally cause a softlockup. To avoid it, call cond_resched() after each cpu buffer allocation. Link: https://lore.kernel.org/linux-trace-kernel/20230906081930.3939106-1-z= hengyejian1@huawei.com Cc: Signed-off-by: Zheng Yejian Signed-off-by: Steven Rostedt (Google) --- kernel/trace/ring_buffer.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 78502d4c7214..72ccf75defd0 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -2198,6 +2198,8 @@ int ring_buffer_resize(struct trace_buffer *buffer, u= nsigned long size, err =3D -ENOMEM; goto out_err; } + + cond_resched(); } =20 cpus_read_lock(); --=20 2.40.1